anyone facing DNS ip change to another ip, which is not set by network admin?

anyone facing DNS ip change to another ip, which is not set by network admin?
I set to 8.8.8.8 and 8.8.4.4 but when i login system see, it auto set to another range ip which is not set by me..
I have few site facing these issue recently..

You should make sure you’re using latest RouterOS and have changed all your passwords. There are several exploits that could have caused this.

Check if the new DNS IP are the same as the ones provided by your ISP.